1. Field of the Invention
The present invention relates to a method of manufacturing a printed circuit board (PCB) and a PCB structure manufactured by the method.
2. Discussion of the Related Art
A PCB, obtained by printing a circuit line pattern on an electrically insulating substrate using a conductive material such as copper, refers to a board before electronic components are mounted thereon. That is, the PCB is a circuit board that defines mounting positions of various electronic components and fixes a line pattern, printed thereon, for connecting the components such that the various electronic components are mounted on the board.
Methods of manufacturing the PCB use photolithography that has advantages of high productivity and low manufacturing cost. Methods of manufacturing the PCB board using photolithography include a subtractive process, a full additive process, and a semi-additive process. Particularly, the semi-additive process draws attraction since it can form a micro circuit pattern.
Referring to FIG. 1, the subtractive process forms a metal layer 2 on an insulating layer 1 (a), coats photoresist 3 on the metal layer 2, patterns the photoresist layer 3 through exposure and development (b), etches the metal layer 2 to form a circuit pattern (c), and removes the photoresist (d).
Referring to FIG. 2, the semi-additive process forms a seed layer 5 on an insulating layer 1 (a), forms a photoresist pattern 3 on the seed layer 5 (b), fills a metal material in the photoresist pattern 3 to form a circuit pattern (c), removes the photoresist pattern (d), and eliminates the seed layer 5 (e).
However, the above conventional processes are difficult to secure reliability in micro circuits because of a variation in patterns during photolithography and adhesion of materials in the micro circuits.
With the recent high integration of semiconductor chips and increase in a signal transfer rate, circuit miniaturization and PCB technology for achieving high electrical property, high reliability and high functionality are required. Accordingly, an embedded PCB having a circuit pattern embedded in an insulator, as shown in FIG. 3, is considered.
Referring to FIG. 3, a conventional method of manufacturing an embedded PCB includes a step (a) of preparing a carrier substrate having a metal layer 20 and an insulating layer 10 supporting the metal layer 20, a step (b) of coating photoresist on the metal layer 20 and patterning the photoresist to form a photoresist pattern 30, a step (c) of filling the photoresist pattern 30 with a metal material 40, a step (d) of removing the photoresist pattern to form a circuit pattern, a step (e) of aligning the carrier substrate on an insulating layer 50 with the circuit pattern 40 facing the insulating layer 50, a step (l) of pressing the carrier substrate against the insulating layer 50 using a press to embed the circuit pattern in the insulating layer 50, a step (g) of removing the metal layer, and a step (h) of removing the insulating layer.
However, the above conventional method of manufacturing an embedded PCB is complicated and it is difficult to perform interlayer alignment for embedding the circuit pattern in the insulating layer. Accordingly, there is a limitation in manufacturing a multi-layer PCB using a conventional manufacturing method.